Wire grooving method and machine

ABSTRACT

Wire stock is given an encircling, coaxial groove by shearing off a pair of slugs of material along equal and parallel chord planes on opposite sides of the wire axis, and pressing the remaining core of material in the direction of the chord planes first from one side and then the other to form the cylindrical surfaces of the groove. The shearing tool preferably includes a semicylindrical, concave die for forming half the groove surface in the shearing stroke, and a die with a slightly larger diameter semicylindrical surface presses from the opposite direction to complete the groove.

United States Patent Inventor David W. Snyder Hilton, N.Y.

Appl. No. 774,751

Filed Nov. 12, I968 Patented May 25, 1971 Assignee Snyder Specialty,Inc.

Hilton, N.Y.

WIRE GROOVING METHOD AND MACHINE 8 Claims, 6 Drawing Figs.

U.S. Cl 72/339, 72/373, 72/464 Int. Cl ..B21d 28/00, B2ld 31/00, B21c3/02 Field of Search 72/338,

[56] References Cited UNITED STATES PATENTS 1,106,741 8/1914 Slick72/331 1,037,867 9/1912 Coe 72/331 3,426,632 2/1969 Ahles et a1. 83/100Primary ExaminerCharles W. Lanham Assistant ExaminerR. M. RogersAttorney-Cumpston, Shaw & Stephens ABSTRACT: Wire stock is given anencircling, coaxial groove by shearing off a pair of slugs of materialalong equal and parallel chord planes on opposite sides of the wireaxis, and pressing the remaining core of material in the direction ofthe chord planes first from one side and then the other to form thecylindrical surfaces of the groove. The shearing tool preferablyincludes a semicylindrical, c'oncave die for forming half the groovesurface in the shearing stroke, and a die with a slightly largerdiameter semicylindrical surface presses from the opposite direction tocomplete the groove.

WIRE GROOVING METHOD AND MACHINE THE IMPROVEMENT EFFECTED Wire rods areused extensively as linkage and lever arms, and a preferred way tosecure them in place is with spring clips snapped into encircling,coaxial grooves formed in the wire rods for this purpose. A familiar useof such rods is in carburetor linkages.

Previously, the retainer grooves in such rods have been cut by screwmachines or machined with fixtures in processes that were relativelyslow and costly. However, since groove formation has long requiredrelative rotation between the work piece and a cutting tool, the screwmachine process has been standard for grooving wire rods.

In an attempt to reduce the expense of groove cutting, opposed flatsurfaces were formed in wire rods to receive the spring clip, but thishas been rejected by the art because of the difficulty of assembly. Aspring clip can be snapped onto opposed flat surfaces from only twodirections, and this made assembly and reassembly especially difi'rcult.

The objects of this invention include, without limitation, formingsmooth, coaxial, cylindrical grooves of reduced diameter in wire by apunching operation that is faster, more efficient and less costly thanprevious groove-forming methods. Screw machines could groove and cut offwire pieces at about 12 per minute, and the inventive punching operationdoes this and other wire forming operations at a rate that has alreadyreached 90 pieces per minute with prospects for increased rates in thefuture.

SUMMARY OF THE INVENTION The inventive method includes: shearing a pairof slugs of material from the wire in the region of the groove along apair of parallel, equal, chord planes on opposite sides of the axis ofthe wire, the distance between the chord planes being less than thediameter of the groove; pressing a first semicylindrical, concave die inthe direction of the chord planes against the core material left betweenthe chord planes to form the core material into a first semicylindricalsurface of the groove; and pressing a second, semicylindrical, concavedie against the core material in a direction opposite to the first dieto form the core material into a second semicylindrical surface of thegroove. Preferably the shearing tool includes the first semicylindricaldie, which has a somewhat smaller diameter than the secondsemicylindrical die.

THE DRAWINGS FIGS. 1-5 are partially schematic elevational views of thepreferred tools shown in operational sequence for forming a wire grooveaccording to the invention; and

FIG. 6 is an elevational view of a wire rod grooved according to theinvention.

DETAILED DESCRIPTION Throughout the specification and claims, theinvention is described relative to formation of a groove in acylindrical wire, the groove being a cylindrical section of reduceddiameter coaxial with the wire. The inventive method and machine canalso be used to form grooves in rod or stock material of across-sectional shape other than circular and to form a groove having acore or surface shape other than cylindrical.

Wire 10 shown in FIG. 6 has a groove 11 formed according to theinvention. As shown in FIG. 5, groove 11 is smooth, generallycylindrical and coaxial with wire 10. The formation of groove II in wire10 is shown in sequence in FIGS. 1-5.

In the first operation, tool 12 is driven against wire 10 as shown inFIGS. 1 and 2. Backup block 13 is arranged on one side of wire 10 andhas a channel 14 of substantially the diameter of wire 10 for centeringwire 10 relative to tool 121 Backup block 13 also has a slot forreceiving tool 12, and passageways 15 communicate with such slot forcarrying away slugs of material sheared from wire 10. Toolholder 16holds tool 12 and is driven in a reciprocal motion toward and away frombackup block 13. A channel 17, also the diameter of wire 10, is formedin the face of toolholder 16 to assist in centering wire 10 relative totool 12.

Tool 12 has an opposed pair of sharp shearing edges 18 and 19spaced-apart by less than the diameter of wire 10, and somewhat lessthan the eventual diameterof groove 11. A semicylindrical sharp-edgeddie surface 20 connects shearing edges 18 and 19 at the back of the slotin tool 12 to form half the cylindrical surface of groove 11.Semicylindrical die surface 20 is formed with a diameter approximatelyequal to the distance between shearing edges 18 and 19.

As tool 12 is driven against wire 10 as shown in FIG. 2, shearing edges18 and 19 shear off an opposed pair of slugs 21 and Y22 of material fromwire 10. Slugs 21 and 22 are drawn through passageways 15 by vacuum tokeep them clear of tool 12. Because wire 10 is centered by channels 14and 17 as it is struck by tool 12, shearing edges 18 and 19 are spacedequally on opposite sides of the axis of wire 10 so that the chordplanes 23 and 24 along which slugs 21 and 22 are respectively removed,are approximately equal, parallel, and equally spaced on the oppositesides of the axis of wire 10.

As tool 12 is driven fully into wire 10, die surface 20 strikes the coreof material between chord surfaces 23 and 24 to press such materialtoward the center of wire 10, and form it into the semicylindrical shapeof die 20. The diameter of the resulting semicylindrical groove surface25 is only slightly less than the ultimate diameter of groove 11.

For the sequence illustrated in FIGS. 35, wire 10 is preferably advancedto a second station to register the previously punched part of wire 10with tool 28 that is held in toolholder 29 on the opposite side of wire10 from too] 12 .to face backup block 30. Centering channels 31 and 32of the diameter of wire 10 are formed respectively across the face ofbackup block 30 and toolholder 29 to center wire 10 relative to tool 28.Toolholder 29 is driven toward-and away from backup block 30 to advancetool 28 onto wire 10' in a punching operation.

Tool 28 has a notch 33 disposed to straddle chord surfaces 23 and 24punched into wire 10, and a sharp-edged, semicylindrical die surface 34is formed at the back of notch 33in tool 28. As tool 28 is driven into aslot in backup block 30 as illustrated in FIG. 4, semicylindrical diesurface 34 punches the core material between chord surfaces 23 and 24toward the center of wire 10 to form such material into semicylindricalgroove surface 35 as illustrated. Channels 31 and 32 center wire 10accurately for such operation so that the semicylindrical surface 25formed by tool 12 and the semicylindrical surface 35 formed by tool 28are substantially coaxial to form the generally cylindrical surface ofgroove 11. Since the sides of notch 33 are slightly wider than shearingedges 18 and 19 of tool 12, tool 28 normally fits over chord surfaces 23and 24, and the core material in the center of wire 10 moves under theimpact of die 34 to form a smooth semicylindrical surface 35 blendingevenly into the semicylindrical surface 25 previously formed.

FIG. 5 shows tool 28 retracted from backup block 30 to illustrate incross section the ultimate shape of groove 11 relative to wire 10.

Passageways 37 are preferably formed in backup block 30 to communicatewith the tool-receiving slot so that ifany error in the advancement ofwire 10 brings tool 28 into contact with an unpunched portion of wire10, the slugs sheared from wire 10 by the edges of notch 33 will bereceived in passageways 37 and not harm tool 28 or backup block 30.

With retractable tools, it is possible within the spirit of theinvention to combine all the operations illustrated in FIGS. 1- 5 at asingle station with a first shearing and punching stroke in onedirection, retraction of this stroke, and a subsequent punching strokefrom the opposite direction that is retracted to complete the operationwithout advancement of wire 10.

A variety of punch-type machines having reciprocating tools can be usedto accomplish the inventive method, and

machine selection depends in part upon other operations that form thewire rod into a finished part. The inventive method has beensuccessfully practiced on machines commonly known in the art asmultislide or fourslide machines.

Persons wishing to practice the invention should remember that otherembodiments and variations can be adapted to particular circumstances.Even though one point of view is necessarily chosen in describing andclaiming the invention, this should not inhibit broader or relatedapplications within the spirit of the invention. For example, the tools,toolholders and backup blocks can be arranged in a variety of ways forthe inventive punching operation which can be accomplished in one, two,three or more stations as desired. Also, those skilled in the art willreadily understand the adaptation of the inventive method of variousknown machines.

l claim:

l. A method of forming an encircling, coaxial groove in a wire, saidmethod comprising:

a. shearing a pair of slugs of material from said wire in the region ofsaid groove;

b. the shear planes for said slugs being two, parallel and substantiallyequal chord planes on opposite sides of the axis of said wire;

c. the distance between said chord planes being less than the diameterof said groove;

d. forcing a first semicylindrical, concave die in the direction of saidchord planes against the core material between said chord planes to formsaid core material into a first semicylindrical surface lyingsubstantially at the surface of said groove;

e. forcing a second, semicylindrical, concave die against said corematerial between said chord planes in a direction opposite to said firstdie to form said core material into a second, semicylindrical surfacelying substantially at the surface of said groove and communicating withsaid first semicylindrical surface to complete said groove surface.

2. The method of claim 1 wherein the diameter of said firstsemicylindrical die equals the distance between said chord planes, andthe diameter of said second, semicylindrical die equals the diameter ofsaid groove.

3. The method of claim 1 wherein said first semicylindrical die isformed as part of a tool for shearing said slugs so that said shearingand said first semicylindrical surface forming occur in a single strokeof said tool.

4. A machine for forming an encircling, coaxial groove in a wire, saidmachine comprising;

a. a first tool;

b. said first tool having a pair of shear edges spaced-apart by lessthan the diameter of said groove; 0. said first tool having asemicylindrical, concave, die suri face joining said shear edges;

d. a first backup block having a channel for locating said wire;

e. said first backup block being disposed on the opposite side of saidwire from said first tool;

f. a first holder for moving said first tool toward said first backupblock to shear a pair of slugs of material from said wire in the regionof said groove along a pair of shear planes that are parallel andsubstantially equal chord planes on opposite sides of the axis of saidwire, and to force said semicylindrical, concave die against the corematerial between said chord planes to form said core material into afirst semicylindrical surface lying substantially at the surface of saidgroove;

g. a second tool having a slot the width of the diameter of said groove;

h. said second tool having a semicylindrical, concave die surfaceconnecting the walls of said slot;

i. said second tool being disposed on the opposite side of said wirefrom said first tool;

j. a second backup block having a channel for locating said wire;

k. said second backup block being disposed on the opposite side of saidwire from said second tool; and

l. a second holder for moving said second tool toward said second backupblock to force said second semicylindrical, concave die against saidcore material between said chord planes to form said core material intoa second semicylindrical surface lying substantially at the Surface ofsaid groove and communicating with said first semicylindrical surface tocomplete said groove Surface.

5. The machine of claim 4 wherein said first backup block is formed withopenings for receiving said slugs of material.

6. The machine of claim 5 wherein said second backup block is formedwith openings for receiving any material sheared from said wire by saidsecond tool.

7. Punching equipment comprising:

a. no change b. no chance c. a holder for punching said first toolagainst a workpiece in one direction and a holder for punching saidsecond tool in the opposite direction against said punched region ofsaid workpiece with said slot of said second tool aligned with the pathof said slot of said first tool.

8. The punching equipment of claim 7 including a backup block disposedopposite each of said tools to support and locate said workpiece.

1. A method of forming an encircling, coaxial groove in a wire, saidmethod comprising: a. shearing a pair of slugs of material from saidwire in the region of said groove; b. the shear planes for said slugsbeing two, parallel and substantially equal chord planes on oppositesides of the axis of said wire; c. the distance between said chordplanes being less than the diameter of said groove; d. forcing a firstsemicylindrical, concave die in the direction of said chord planesagainst the core material between said chord planes to form said corematerial into a first semicylindrical surface lying substantially at thesurface of said groove; e. forcing a second, semicylindrical, concavedie against said core material between said chord planes in a directionopposite to said first die to form said core material into a second,semicylindrical surface lying substantially at the surface of saidgroove and communicating with said first semicylindrical surface tocomplete said groove surface.
 2. The method of claim 1 wherein thediameter of said first semicylindrical die equals the distance betweensaid chord planes, and the diameter of said second, semicylindrical dieequals the diameter of said groove.
 3. The method of claim 1 whereinsaid first semicylindrical die is formed as part of a tool for shearingsaid slugs so that said shearing and said first semicylindrical surfaceforming occur in a single stroke of said tool.
 4. A machine for formingan encircling, coaxial groove in a wire, said machine comprising; a. afirst tool; b. said first tool having a pair of shear edges spaced-apartby less than the diameter of said groove; c. said first tool having asemicylindrical, concave, die surface joining said shear edges; d. afirst backup block having a channel for locating said wire; e. saidfirst backup block being disposed on the opposite side of said wire fromsaid first tool; f. a first holder for moving said first tool Towardsaid first backup block to shear a pair of slugs of material from saidwire in the region of said groove along a pair of shear planes that areparallel and substantially equal chord planes on opposite sides of theaxis of said wire, and to force said semicylindrical, concave dieagainst the core material between said chord planes to form said corematerial into a first semicylindrical surface lying substantially at thesurface of said groove; g. a second tool having a slot the width of thediameter of said groove; h. said second tool having a semicylindrical,concave die surface connecting the walls of said slot; i. said secondtool being disposed on the opposite side of said wire from said firsttool; j. a second backup block having a channel for locating said wire;k. said second backup block being disposed on the opposite side of saidwire from said second tool; and l. a second holder for moving saidsecond tool toward said second backup block to force said secondsemicylindrical, concave die against said core material between saidchord planes to form said core material into a second semicylindricalsurface lying substantially at the surface of said groove andcommunicating with said first semicylindrical surface to complete saidgroove surface.
 5. The machine of claim 4 wherein said first backupblock is formed with openings for receiving said slugs of material. 6.The machine of claim 5 wherein said second backup block is formed withopenings for receiving any material sheared from said wire by saidsecond tool.
 7. Punching equipment comprising: a. no change b. no chancec. a holder for punching said first tool against a workpiece in onedirection and a holder for punching said second tool in the oppositedirection against said punched region of said workpiece with said slotof said second tool aligned with the path of said slot of said firsttool.
 8. The punching equipment of claim 7 including a backup blockdisposed opposite each of said tools to support and locate saidworkpiece.